What is rational? Is not rationality subjective? What you might deem irrational others might deem perfectly rational, and vice-versa, what you might deem rational others might deem quite obviously irrational.
Are we to see experiences as rational explanation of a phenomena? Sure, I see and feel a rock, and I verify its existence rationally. I smell food and verify its existence rationally. What about people experiencing a divine being communicating to them, then?
No, we must disregard this as hallucination or a psychological problem. Only what we (and by we I mean the "educated western world") in our pre-determined frame of rationality deem rational can ever be rational, and all that falls outside must naturally be considered irrational irrespective of its potential rationality in relation to other experiences we might call rational.
Really (I think), something being rational is a state of mind, a common understanding with our peers. In a church most would agree that their belief is rational, not out of ignorance (though here you might disagree), but out of shared acceptance of a different frame of rationality, essentially accepting other experiences as being able to feed to rationality than those you might accept.
I guess the point I'm trying to make (and I might be way off) is that when you say that religiosity espouses irrationalist beliefs, they're irrational to you, within your frame of rationalism. To someone else you're the ignorant one who's fighting tooth and nail.
Edit: To those down voting I would love to engage further in conversation about this!